


Those Idol Outfits Are Dangerous

by ruff_ethereal



Category: BanG Dream! Girl's Band Party! (Video Game)
Genre: Alternate Universe - Role Reversal, Band Switch, Clothed Sex, F/F, Incest, Lactation, Light Angst, POV First Person, Twincest, Vaginal Fingering
Language: English
Status: Completed
Published: 2020-06-08
Updated: 2020-06-08
Packaged: 2021-03-04 06:01:57
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,889
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24598711
Author URL: https://archiveofourown.org/users/ruff_ethereal/pseuds/ruff_ethereal
Summary: Hina has always been very inappropriately obsessed with Sayo and the flashy, cutesy outfits she wears as the guitarist of Pastel*Pallettes. Though Hina has kept all these fantasies and urges inside for months, things come to a head when Sayo comes home wearing Hina's favorite design.
Relationships: Hikawa Hina/Hikawa Sayo
Comments: 16
Kudos: 48





	Those Idol Outfits Are Dangerous

**Author's Note:**

  * For [sayohjna](https://archiveofourown.org/users/sayohjna/gifts).
  * Inspired by [Mistaken Identity](https://archiveofourown.org/works/24551533) by [tinygaydream](https://archiveofourown.org/users/tinygaydream/pseuds/tinygaydream). 



> There will be lactation and the girls are both unshaven down there. Sorry if that bothers you, especially if you were expecting a relatively vanilla SayoHina smut fic.

I don't know how the corporations and the fans could think that Pastel*Palettes was a family-and-advertiser-friendly band when their normal stage outfits were this revealing.

Such huge, frilly, and poofy skirts that bounced up and about with their energetic, sugar-pop choreography. All those exposed thighs and legs even when they weren’t dancing. And don’t even get me started on their debut outfits that exposed their shoulders and their armpits, those always seemed to be just one snag or a too-energetic move away from a major wardrobe malfunction.

Not that I was complaining!

I wanted them to get even racier and revealing with their outfits. Push the boundary of what they could show live on television and on-stream. The higher-ups were only giving the okay to these designs because it let them milk money from hordes of horny guys and girls, and I was all too happy to fork it over to see more of the band.

To be honest, though, I was only really here for Sayo.

There was nothing I wouldn’t have given for the chance to see her up close in full stage outfit. To get to touch her clothes and see just if they were as satiny, smooth, and soft as I imagined them. And of course, I’d love to also get the chance to make my numerous naughty fantasies about her a reality.

But I wouldn’t do that.

Because I didn't want to ruin Pastel*Palettes' musical success by a nuclear-level scandal like that.

Because Sayo definitely wouldn’t agree to any of it no matter how much was offered.

Because I was Hina, her twin sister, who she hated and wanted out of her life.

So I obediently stood in the audience, well behind the security barrier, wearing officially licensed Pastel*Palette merchandise both because it had Sayo on them and they would help me better blend in with their hordes of fans wearing the same thing.

So I lied about sneaking into their concerts, I lied to the stupidly-tight-but-not-tight-enough security that worked their concerts, and I lied to Sayo’s face whenever she asked.

So I kept all these fantasies about her and her boppin’ idol outfits deep inside.

I knew this was all a terrible idea.

I was enough of a genius to know that it was the moment I decided to sneak into my first Pastel*Palettes concert, too stubborn to admit that it would fail on me like it did everyone else who tried, too confident in my ability to find a solution just before it all inevitably came apart.

But oh, how the proud fall.

It all started on a pretty normal night. Our parents were off for a work thing, said they expected to be coming home past midnight at the earliest, so don’t bother waiting for them. Sayo was out for a PR event as well, a “flash meet-and-greet” in the city.

I had already long finished my Student Council duties, and with everyone else unavailable, I was now trying to figure out how to spend the rest of the day by myself. I was channel surfing in the living room when I heard the door open.

“I’m home,” Sayo said flatly.

I launched off the couch and rushed to her. “Welcome home, Big Si—huh?”

Sayo was still wearing her band outfit. Not just _any_ band outfit, either, but the one from the “Blooming Yell” set, one of my absolute favorites for just how cute _and_ sexy she looked, with all the ruffles of her dress, the vibrant colors, how well it fit her body, and how much of her wonderful skin it exposed.

She’d ditched almost all of the accessories that could come off plus the half-gloves, but honestly, I was glad for that—she looks so much better this way, without all the shiny trinkets distracting from her beauty.

“There was an accident at the venue...” Sayo muttered, blushing and looking away. “My regular clothes got ruined and I decided to go home in this than wait however long it would take the staff to find replacements...”

Crap, crap, crap, I was staring just now, wasn’t I?

“I see. That sucks! Well, welcome home, Big Sis!” I said, trying to feign calm. “Bath’s free if you need it. Should I go get you some fresh clothes?”

“Not right now because I could use your help with something else,” Sayo said. “This dress zips up at the back; I can’t reach it myself and I don’t want to risk damaging anything trying.”

“Oh, okay!” I said, just barely keeping my voice calm.

I was in a whole world of trouble.

Sayo had stopped bathing with me for years now and it was one thing I was _glad_ she did. My fantasizing about her could get vivid and heated enough with glimpses of bare skin I got while she was on-stage and _especially_ that PR thing when they were all in their swimsuits. I don’t know how much worse my obsession would get if she was completely naked and within arm’s reach.

I suppose I was going to find out whether I wanted to or not.

People called me a genius, but I couldn’t find a way to get out of this with my secret safe, our dignities intact, and suspicions at a minimum. What do I even do? Close my eyes and hope Sayo doesn’t look back, using the sensation of the zipper hitting the bottom to know that I was done? Zip it down in one go like the tablecloth trick then disappear like magic as well?

We were at the changing room/laundry area outside the bathroom before I could come up with anything _good_.

Sayo sighed heavily, gathered up her hair, and flipped it over her shoulder; I knew she was just revealing the zipper and keeping her hair safe, but I still got a huge whiff of the perfume she was wearing. Probably something she was contractually obliged to use as part of a brand deal or for the sake of the meet-and-greet, but _wow_ , did she smell zappin’.

“You can start now,” Sayo muttered.

Moment of truth. I steadied my shaking hands, grabbed the zipper, and began to _very_ slowly pull it down. Not because I wanted to savor gradually exposing her back, no, _no,_ it was because Sayo was right: this thing probably cost a whole lot of money and the studio wasn’t going to be happy if it got dama--

“… Is something wrong, Hina?” Sayo asked quietly.

“Big Sis, you’re not wearing a bra?” I sputtered.

“No,” Sayo replied. “Why would I? It’s not as if I need the support anyway.”

And people called _me_ oblivious and blunt to a fault.

I got it halfway down now, her shoulders were exposed, the top was beginning to slide off and down her arms, when--

“What was that noise?” Sayo asked.

“I think the zipper’s stuck,” I said as I tried to give it a few more experimental tugs—yep, pretty tightly jammed, but thankfully not on Sayo’s skin.

“Oh, are you kidding me?!” Sayo yelled. “They tell us we can’t afford to mess up any shows because of how much money the investors pour into our performances, yet they can’t find space in our bloated budgets to afford half-way decent zippers for their talent’s stage outfits?!”

I was too entranced by the sight of her back and the knowledge she was bra-less to comment.

Sayo took a few breaths to calm herself. “Hina… I’m sorry, but I’ll need you to get more involved with getting this off.”

I gulped. “Got it…!” I said as I slipped my hands into her clothes through her shoulders. The fabric felt soft and satiny, Sayo’s skin felt smooth and warm, my hands felt like they were on fire and getting electrocuted at the same time.

Sayo put her arms tight against her sides, I started to very carefully push and tug her outfit down. It was so perfectly sized and tailored to her figure that my hands were constantly in contact with Sayo’s body, it seemed impossible to get this dress off comfortably unless that zipper was completely down.

“Ahh…!” Sayo squeaked.

She stiffened up, I did too. The two of us stayed frozen, both of us _well-aware_ that my hands had gotten stuck right over her breasts, I couldn’t go any further down without risking ripping something.

Crap, crap, crap. They felt better than I’d ever imagined, couldn’t compare to my fondling myself.

Stop, stop, stop. Stop thinking about that, just get your hands out.

Wait, wait, wait. Were her nipples getting _hard?_

“… Hina...” Sayo whispered, her voice nervous, her breathing shallow.

This was it. Game over. Curtains closed.

Roselia was going to have to find a new guitarist because there was no way I could ever be in such a public role ever again, I needed to completely and utterly disappear from Sayo's life, I would never be able to look her in the eye or be near her ever again.

"More..." Sayo moaned before she squeaked and shut her mouth.

I blinked. “Big Sis…?”

“Ah--!” Sayo gasped. “Forget it, forget I said anything, forget any of this happened--!”

“Big Sis.”

Sayo went quiet. I could feel her shaking and trembling from fear, she was probably sweating bullets as well.

I leaned in over her shoulder and whispered into her ear, “Do you want more? Because I’d love to give you more.”

Sayo stiffened up again.

I braced myself. Point of no return. Anything could happen at this point.

Sayo sucked in a deep breath then whispered, “… Please.”

My hands were moving in an instant: carefully nudging and moving her clothes to give myself more space to fondling, groping, and rub her breasts, special focus on her rock-hard nipples.

Sayo moaned and shivered, reached out and pressed her hands against the wall as her knees began to quake.

“Do you like this, Big Sis?” I whispered as I pressed up closer to her, spread my feet for a more comfortable stance.

“Yes, k-keep going,” Sayo whispered, nodding.

I did as she asked, burning into my mind just how her breasts felt in my hands, the texture of the inside of her outfit, the un-Sayo-like sounds she was making as I groped and felt up her breasts. I decided to give them a little, gentle squeeze—then stopped as I felt something warm and wet trickle out onto my fingers.

“Oh, why now of all times?!” Sayo hissed.

I blinked, squeezed again, and felt the same sensation.

Sayo yelped. “Hina, stop!” she snapped. “You’ll make me leak worse!”

“Is this milk?” I asked. “Are you _lactating?”_

“… Yes,” Sayo said. “It’s a side-effect of my birth control pills. I’m sorry, you must think this is _disturbing.”_

“No, I think it’s _super_ boppin’, actually,” I said.

“… Seriously…?”

“I don’t think you’ve realized I’m kind of super kinky, Big Sis.”

Sayo sighed. “I’m terribly disappointed in myself for being terribly happy to hear that.”

“Zappin’,” I hummed as I slipped my hands off her breasts and out of her clothes.

“Hina?” Sayo asked as she looked back.

“Turn around for me?” I asked.

Sayo gave me an annoyed look, before she sighed, slowly turned around, and stood with her back against the wall. Oh, she looked so _boppin’,_ looking pissed and embarrassed with her arms crossed over her stomach, the loosened top of her dress exposing her shoulders and her leaking breasts as they hung off her arms, wet, dark spots spreading all over the white-and-blue fabric.

“Happy?” she asked.

I felt a zappin’ sensation run down my spine. “Very,” I said as I stepped up to her. “Can I kiss you?”

“… Yes.”

I planted my hand on the wall beside her head, cupped her chin with the other. Sayo began to reach out and hold onto my waist, as much as her outfit would allow. The two of us looked into each other's eyes, mine excited, Sayo's nervous.

“Do you still want to, Big Sis?” I whispered.

“Yes.”

We both leaned in and kissed.

I wouldn’t call it boppin’ or zappin’--it just wouldn’t describe how _amazing_ it felt. It was just a quick, light, _almost_ innocent kiss, but with all the pent-up desire behind it, it meant _so_ much more. The skin of my lips tingled as we pulled away, Sayo’s were trembling as she tried to say something but couldn’t quite do it.

“Want me to go back to your breasts, Big Sis?” I asked.

Sayo closed her mouth then shook her head. She reached down and lifted up the front of her skirt; I looked down and found her plain white panties soaked dark. “Please touch me down there as well,” she mumbled, blushing and looking aside.

“With pleasure,” I said.

I took some time to carefully pull Sayo’s panties down her thighs, savoring the noises she made, the way she quivered and leaked as I exposed her pussy. I ran my fingers over the rough patch of hair above them before I slipped my hand between her legs and touched her.

“Ahh--!” Sayo gasped, jumping up, one of her hands letting go of her skirt, the fabric fell over my forearm.

She tried to pick it back up, I told her: “No. Let it all go. I think it’s more boppin’ this way.”

Sayo looked unsure but she did as I asked. Her hot, wet pussy lips on my fingers, the delicate, fluffy ruffles of her skirt on my wrist and forearm—it was a totally zappin’ combo.

I reached up to her breast with my other hand, leaned in, and brought my face close to her so I could see every last detail on her face as her expressions changed, feel her hot breaths on my cheeks, hear all the boppin’ noises she’d start making pretty soon.

“Are you ready, Big Sis?” I ask.

Sayo bit her lip and nodded furiously.

I started slowly rubbing her pussy, felt her tremble, start to leak all over my fingers and the palm of my hand. The flow of warm, creamy milk spilling out of her breasts got even stronger even before I started groping, squeezing, and toying with them again. Her dress must have been soaked from all these fluids, and the thought of it completely ruined and reeking of sex and milk was getting me even more excited.

“H-Hina...” Sayo moaned as a powerful shiver ran down her body, she stood with her hands by her sides, palms-out and unsure of what to do with them.

I had to kiss her again, trap her lips in mine, show her just how much more I wanted her now. She gasped and stiffened before she quickly yielded, heated moans and embarrassed squeaks dying in her throat. I pulled away first, and while Sayo was gasping for air, I went down and wrapped my lips around her free breast.

“Hina!” Sayo gasped.

Her milk tasted so sweet and creamy, I hungrily suckled and licked for more, trying to get as much of it into my mouth as possible. Sayo started jerking her hips, I slipped my finger inside and started pumping. The two of us soon hit a wild, passionate rhythm, the hall echoing with the wet sounds of sex, her moans and gasps, my hungry gulps.

“Hina…!” Sayo screamed just before she came, hips bucking, milk gushing from her breasts and all over our clothes, her arousal spilling out all over my hand and my wrist, trickling down her thighs and onto the floor.

She was going so wild I had to stop, just held steady and sure until she began to slowly calm down.

I pulled my hands away, Sayo began to sink against the wall. I grabbed her and pulled her onto me, hugged her as I held her upright. “I love you, Big Sis,” I whispered.

“… I love you too, Hina...” Sayo whispered back.

Sayo asked to sit down on the floor to recover, so I went off to go find the bottle of machine oil we used for the door hinges. With it, I finally got the zipper unstuck, but by that point, her dress was soaked in several places, wrinkled all over, and part of the flower ornaments it had cracked and broken from wild we got.

“My agency’s not going to be happy about this...” Sayo muttered as I held it up for inspection.

“I’ll figure out some way to get it good as new!” I said as I carefully folded it up. “You just focus on getting a bath, I’ll take care of it plus everything else, Big Sis!”

Sayo blushed. “Thank you, Hina. Also…” she looked away, “after my bath, meet me in my room; we need to sit down and have a serious discussion about what just happened.”

“I’ll be there,” I said.

I had that familiar not-boppin’ feeling in my stomach that we weren’t going to do anything nearly as fun as what just happened—but, I was still going to go.

Because I knew it would be _way_ worse if I disappeared on her and hid out in my room.

Because I knew I had to come clean about everything I’d done before this moment.

And most importantly, because I loved her.

**Author's Note:**

> My apologies, I haven't written smut in too long and feel unconfident in my skills.


End file.
